An Improved Decentralized Control of Grid-Connected Cascaded Inverters with Different Power Capacities

TL;DR

This paper introduces an improved decentralized control method for grid-connected cascaded inverters with varying power capacities, enhancing synchronization, power factor control, and fault immunity, validated through experiments.

Contribution

It proposes a novel decentralized control scheme that adjusts voltage amplitudes based on individual inverter capacities and ensures phase synchronization.

Findings

Effective voltage amplitude variation according to power capacity

Achieves autonomous phase synchronization and power factor control

Demonstrated robustness against grid voltage faults

Abstract

The existing decentralized control for cascaded inverters is based on the assumption that all modules have same capacities, and a local fixed-amplitude-varied-phase voltage control is adopted for each inverter module. However, available source power capacities of cascaded inverters may be different in some practical applications. To address this issue, this letter proposes an improved decentralized control scheme, in which the voltage amplitudes are varied according to their individual available powers. Moreover, a power factor consistency control is proposed to achieve autonomous voltage phase synchronization. The steady-state analysis and synchronization mechanism of cascaded inverters are illustrated. In addition, the proposed strategy has other advantages, such as adjustable grid power factor and immune to the grid voltage fault. The effectiveness of the proposed control is tested by experiments.